Radio range indicating system



Oct 11, 1955 J. E. SHEPHERD ET AL 2,720,647

RADIO RANGE INDICATING SYSTEM Original Filed April 30, 1942 4Sheets-Sheet l ft-9. L Q 3 GUNS COMPUTER 3 7R19@ V6 L Mo/V/ TOR l lREcE/ VER I L- I u TRR/vsM/TTE/e EAW/VER l 4! MON/TOR J6 RRA/6E Z 9)CoA/7R01. 10

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' INVENTORS @ff-FUR@ E. WH/ TE JH/W5S E. SHEPHERD BY Oct. 1l, 1955 J. E.SHEPHERD ET AL RADIO RANGE INDICATING SYSTEM Original Filed April 501942 4 Sheets-Sheet 4 L/TU COMPUTER F a /4 R40/V65 CONTRL 33 .9

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RADIO RANGE INDICATING SYSTEM .lames E. Shepherd, Hempstead,vN. Y., andGifford E. White, Woodland Hills Calif., assignors to Sperry RandCorporation, a corporation of Deiaware Original application April 30,1942, Serial No. 441,188. Divided and this application March 17, 1948,Serial No. 15,398

9 Claims. (Cl. 343-13) with the target and thereby derives the propergun aiming data for controlling the gun turrets. Up to the present time,however, such inter-aircraft fire control devices, and alsoanti-aircraft tire control devices, have relied upon visual tracking ofthe target for determining the correct gun aiming angles. Such prior artsystems are subject to the well known limitations of visual sighting,such as reliance upon proper weather and visibility conditions, uponsuticient lighting, and upon the restricted range of optical telescopes.Even under optimum conditions of visibility, the visual detection of theapproach of aircraft and visual tracking with aircraft have been diicultand uncertain. For instance, aircraft approaching from the direction ofthe sun can be seen only with the greatest dihculty. Furthermore, theobserver cannot scan the whole zone of danger quickly and carefully withcertainty by the eye alone. v

In order to overcome these and other disadvantages of the prior systems,the invention of parent lapplication Serial No. 441,188 provides asystem in which the target is detected, located, and tracked by a radiobeam which effectively replaces the visual line of sight of priorsystems. However, before describing the present system, certainessential requirements for such a system will be discussed.

Firstly, the defending aircraft must be appraised of the presence andapproximate direction or orientation of all targets in its vicinity inorder to be able to effectively plan and accomplish its defense. Inaddition, it is desirable that the approximate rangeof'each of thesevarious targets should be indicated simultaneously with its location,for similar reasons. After having been warned of the presence,orientation, and range of these targets, and after having chosen one ormore of themas of greater importance for immediate engagement, it isnecessary for the particular target selectedto be tracked by the firecontrol system in order to determine the targets present position, suchas defined by its elevation, azimuth, and range, in the present case,and to determine the rate of change of position, as defined by targetelevation rate and azimuth rate, Vin order that the correct gun aimingangles for controlling the guns andturrets may be derived by thecomputer. Y

In order to relieve the fire control officer of as much of the burden oftracking as is reasonably possible, it is desirable to automaticallytrack .withrthe target, at least in elevation and azimuth, and possiblyalso in range, so

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as to automatically set into the computer mechanism the proper targetposition and target rate data.

The present system offers an improved type of range measuring warningsystem for use in combination with several types of tracking or recontrol systems. Preferably, since space and weight are at a premium inaircraft, these various systems are combined as much as possibie to usea minimum amount of equipment.

Accordingly, by the present system there is provided apparatus forindicating the range of any selected target within a predeterminedportion of space.

Upon selection of a particular target, as shown in parent applicationSerial No. 441,188, any one of three different types of tracking systemsmay be used: (l) a system in which the fire control ofiicer actuates thecomputer setting in such a manner as to maintain a radio line of sightin track with a target, (2) a system in which a radio line of sight isautomatically tracked with a target and the fire control officeractuates a computer to maintain it in synchronism with the radio line ofsight, and (3) a fully automatic system in which a radio line of sightis automatically maintained in synchronism with the target and serves toautomatically set into the computer the proper target data required bythe computer.

By such a system both the warning and tracking may be performed entirelyindependently of any optical visibility conditions and at a much greaterrange than was formerly possible, without impairing in any wayr any ofthe desirable features of former types of fire control systems.

In addition, the operation of the present system is made to agree insubstantially all operations to be performed with the operation of priorsystems and the natural instinctive reactions of the operator areutilized by the provision of controlling operations which are naturallydictated by the circumstances encountered.

It is an object of the present invention to provide improvedradio-operated gun control systems.

VI t is still another object of the present invention to provideimproved radio-directed gun control systems for determining the range ofa target.

1t is a still further object of this invention to provide a system formeasuring the range of or distance to a selected target employing avisual indicator for the guidance of the operator in making themeasurement.

A further object of the present invention resides in providing a systemof the foregoing character in which'two electrical waves are phasecompared by generating a local wave in timed relation to one of saidelectrical waves and matching it with the other of said electrical waveson the screen of a cathode ray tube whereby to provide a measure of therelative phase of the two electrical waves or a measure of the timedifference therebetween.

It is a further object of the present invention to provide apparatus formeasuring the time difference between a rst radio wave and a secondradio wave, related in time to the first wave, by means of a cathode raytube wherein a base trace is produced on the face of the tube in timerelation with the first wave, a reference or index square wave beingalso produced in time relation with the first wave and of greater lengththan the second Wave such that, when applied to the deilecting means ofthe cathode ray tube, the index wave representation has a flat topportion which is displaced from and is parallel to the base trace andthe second wave representation is in the form of a pip extendingsubstantially perpendicularly from the base trace, and whereinphase-adjusting means is provided for adjusting the phase relationbetween the index wave and the second wave whereby their representationsmay be relatively shifted so as to place the second wavev operable withthe phase-adjusting means, is provided for producing a measure of thetime difference'b'etween the first and second wave when the index andsecond wave representations are sopositioned.

`""r/rnther object' resides in providing a system of the foregoingcharacter Vembodying a cathode ray tube, on tl'iescree'n of lwhich thereflected pulses and a reference wave may be relatively shifted so as tobe matched or Sopr'edeterminately positioned with respect to each otheras'toprovide `a measure of range to the target.

vAnother object resides in providing a range measuring system in' whichthe appearance of a chosen reflected pulse o'n the screen'of a cathoderay tube may be variably modie'd'there 'along'so that, when modified ina prescribed manner, the means by which it is so modified will.providean indication'of the range to the target reflecting said'pulse.

It4 is ajfurther object of the present invention to provideimproved'devices for setting a member, such as a range control member of acomputer, in accordance with the distance or range to a distant object.

4`'Other objects and advantages of the present invention will 'becomeapparent from the following specification and drawings, in which,

:7 Fig. 1 shows a block or flow diagram of the system of the inventionduring searching operations.

.'xFi'g. `2 shows a corresponding block diagram of the systemduringmanual tracking operations.

Fig. 3 shows a corresponding block diagram ofthe system duringA manualautomatic operations.

Fig.' 4"shows a block diagram ofthe system during full automaticoperations.

""Fi'g. 5 shows a schematic perspective view of one form of scanneruseful in the present system.

Fig. 6 shows-the radiation pattern of the directive antenna array usedwith the scanner of Fig. 5.

"Figg 7 shows a longitudinal cross-sectional view of the radiationpattern ofthe scanner of Fig. during any of thetra'cking operations.

Fi'g."7A is a cross-section of Fig. 7 taken along lines 7A-7A thereof.

Fig, -8` shows a schematic block wiring diagram of one form` ofradio'transmitting, receiving and indicator circuit for searchingoperations.

Fig. 8A shows a representative view ofthe cathode ray screen of theindicator of Fig. 8.

tFig. 9 shows a schematic circuit diagram of the; spiral sweep orreference voltage generating apparatuslfor the circuit of Fig. 8.

"'Figs. 10A, 10B, 10C, and 10D are voltage-time graphs useful'inexplaining the operation of the circuit ofFig, 9.

Fig. ll shows a modication of a portion of the `circuit of Fig. 9 totheright of line /A-A thereof.

` Fig."12 shows a block circuit diagram ofone formof apparatusforcontrolling the scanner orientationfrorn'the computer setting, as duringsearching or manual tracking operations. Y Y

Fig. 13 shows a block circuit diagram of one form of range indicatingsystem.

Fig. 13A shows a representative indication produced by the system ofFig. 13.

Fig. 14 shows a modification of the range indicating system of Fig. 13.

Figs 14A and 14B show alternative types of indication produced by thesystem of Fig. 14.

Although we have herein described our invention in connection with a guncontrol system and particularly in connection with a more comprehensivesystem, more fullydescribed in parent application Serial No. 441,188, itis to be understood that our present invention is not necessarilylimited to such use'but may be employed'in other indicating systemsinvolving different parameters.

As discussed above, the system to which thefpresent invention relates isadapted for two major types of 0p-r eration, namely 1) a searchingoperation forroughly indicating the position and/or distance of anytargets within 'th'eld of operations of the device and (2) a trackingoperation in which a particular target may be selected and followed bythe device for properly directing a gun thereat. Three alternative typesof tracking operation, known as manual, semi-automatic, and fullautomatic tracking maybe-used.

For describing generally these various types of operation, recourseishad tov` Figs. 1-4, more specific details of the system beingdescribed-with respect to later ligures.

Fig. 1 shows a block or flow diagram of the present system whenoperating` during searching. In this system, a scanner 1 projectsl asharply directive beam of radiant energy, such as 19 in Fig. 6, obtainedas from a suitable transmitter 2 anddirective antenna arrangement 3.This beam comprises a'peri'odic sequence of short duration pulses ofhigh frequency energy, and during searching is swept. in a spiral coneover a predetermined solid angle, whichis preferably substantially ahemisphere, in such manner that the radiant energy is projected at sometime during its cycle into every,Vv part of the solid angle. Should anyobject or target be located in this solid angle, theprojected radiantenergy will be reflected therefrom when the beam is directed thereat,and will be received in the samel antenna system 3, which acts dually asa transmitting and a.receiving system.

"'Ihisrellected. seriesof pulses of high frequency energy is,received'in a radio receiver. 4 whose output actuates a suitableindicator. 6r. This'indicator, as will be described belowrmore indetail, ispreferably a cathode ray tube whose electron beam trace iscaused to sweep in spirals in synchronism with and instantaneouscorrespondence with the spiral scanningA motionfof the scanner. For thispurposeitheindicatorr 6v is also-controlled from scanner 1. Thevreceivedrellected pulse is caused to momentarily brightenthe trace` ofthe beamand thereby produce on the cathoderay screen-an indication of theexistence and approximate orientation of the reflecting object. Theapproximaterrange ofthe` reflecting object may also be shownt.'Iheiorientationof the .scanner 1, which may be taken to .bethe.orientation of the polaraxis of the spiral conical scanning-motion, isplaced under the control of a computer 7, whose elevation and azimuthsettings may be manually actuated from a suitable manual control 8.Computer 7. isadapted to calculate the proper gun aimingangles`,for.-intercepting-the target byy a projectile when the computerAis set inaccordance with the present target position data, such. aselevation, azimuth and range of the target, and in accordance with therate of change of the presenttargetpositiorg such as elevation rate andazimulthgs'ratg lA. suitabletorm for such a computer is shown more indetail in copending application Serial No. 411,185, for. Inter-aircraft;Gun SightV and Computer, led September. 17, 1941, in thenames of. C. G.Holschuh and D.`.1"ralrn, now.abandoned.- Asfis shown in thiscopendingapplication, the range settingof computer 7 may be performedYby aysuitable foot ypedal 10. The orientation control Visehtfectedbyathandle barcontrol 8 whose displacementabout two independent axesrepresents a combination ofrpthe displacement rand ratel of change ofdisplacementl of azimuth/,and elevation settings of computer 7,-providing aidedgtracking. Ini operation, the controllingotiicersactuates contrgolgL so asto maintain the present targetpositionsettingof the computer 7 in track with the target, Ias,evidenced ,(inl the-,prior application) by a suitable. opticalsightingarrangement. ByA so doing, the proper` targetgelevation, targetazimuth,target elevation rateandtargetgazimuth rate areisetinto the computingmechanism 7-togetherwith the range data set in by foot pedal 10, wherebycomputer 7 may determine the gun aiming angles. -In,the.p1.esent system,the same operations are,perfort ned, but. utilizing adifferent type. ofindicator. to.. shcw.f.the;proper,tracking/conditions, as will bedescribed.

The scanner 1 is suitably controlled, as Will be seen hereinafter, inaccordance with the target elevation and target azimuth setting ofcomputer l7.v The gun aiming angles determined by computer 7 are used tosuitably control the orientation of one or more guns or turrets 9, whichare thereby rendered effective against the target.

A suitable type of gun control apparatus for orienting the guns 9 underthe control of the computer 7 is shown in copending application SerialNo. 424,612, for Hydraulic Remote Operating Systems, tiled December 27,1941, in the names of E. L. Dawson, F. M. Watkins and C. N. Schub, Jr.,which issued on July 27, 1948 as U. S. Patent No. 2,445,765. It is to benoted that the present system is not confined to the use of thisparticular type of gun control apparatus, but' that any other suitabletype of remote control system may also be used. If desired, the guns 9need not be directly controlled from computer 7-but may be locallycontrolled in accordance with suitable indications transmitted fromcomputer 7 in any well known manner.

The system as shown in Fig. 1 is'not intended for use as the actual guncontrol system but is merely intended to search out possible targets andto enable the scanner to` properly locate a target for the purpose oflater tracking with it. For this reason, the control from computer 7 toguns 9 is shown dotted in Fig. 1. After a target is observed on thescreen of cathode ray indicator 6, the manual control 8 of computer 7 isactuated to adjust the orientation of scanner 1 to the position wherethis orientation coincides as closely as possible with the orientationof the desired target, as evidenced by the position of the bright spotindication on the indicator screen. When this adjustment has been made,the system is ready to change-over to the tracking operation.

The system is adapted to use three separate and distinct types oftracking, any one of which may be selected at the option of the tirecontrol oicer. It is to be noted that each of these types of trackingsystem may be used independently of the others if desirable. For all ofthese types of tracking operation, scanner 1 is energized fromtransmitter 2 by the same type of periodic pulse wave as described-withrespect to the searching operation. However, scanner 1 no longerperforms spiral scanning as in Fig. 1 but instead it is converted toperform a narrow circular conical scanning with a very small apex angle.Preferably, this angle is of the order of the angular width of theradiation and reception pattern derived from antenna 3, indicated inFigs. 6, 7 and 7A.

Thus, if antenna system 3 is adapted to produce a beam of radiant energyhaving a ldirective radiation pattern such as 19 in Fig. 6 with adirectivity Vaxis 21 then, during tracking, beam 19 will be 'rotated Vbyscanner 1 about an axis such as 23 in Fig. 7, whereby directivity axis21 performs a conical motion about axis 23, which may be termed thetracking directivity axis since it is this axis which delines the radioline of sight, as 'will be seen. Preferably, radiation pattern 19 ismade to have a small apex angle such as of the order of 4 in angularwidth between the half-power points. Then, during tracking, the conedescribed by axis 21 would preferably have an apex angle also of theorder of 4. In this manner, the useful portion of the radiant energywould be projected over a conical solid angle having an 8 apex angle.Energy reflected from an object or target within thelield of thisradiant energy will be received by antenna arrangement 3 and led therebyto receiver 4 whose output actuates the tracking indicator 6' toindicate the relative displacement between the scanner orientationdefined by' axis 23 and the orientation of the target.

In the system of Fig. 2, manual actuation of computer control 3 servesto set azimuth and elevation data into computer 7 and at the same timecontrols the orientation' of scanner 1, as determined by axis 23, toassume the same azimuth and elevation as is set'into' computer 7, in the:samemanner as vdescribed with respectto Fig.` 1'.

6 In effect, the orientation of scanner 1 is made the same as theorientation of computer 7, the latter term meaning the orientationcorresponding to the azimuth and elevation data set into the computermechanism:

' VAlso actuated from receiver 4 is a range indicator 6". A matchingindex is provided for indicator 6", as will be described more in detailbelow, which is placed under the control of range pedal 10 serving alsoto set range data into computer 7.

In operating the system of Fig. 2, the operator will, by his manualcontrol 8, orient scanner 1 until the tracking Vindicator 6 shows thatthe target orientation coincides with the scanner orientation. At thesame time, the operator actuates the range foot pedal 10 to match therange index to the indication produced by range indicator 6". When theseconditions obtain, and are maintained even during the motion of thetarget, the operator will know that the proper data is set into computer7 and that the guns 9 controlled from the computed output of computer 7are directed at the correct aiming angles to intercept the target with aprojectile, and he may therefore, by a suitable tiring key or control,fire at the target.

This system is known as manual tracking since the operator, through hismanual control 8 and foot pedal 10, directly actuates the scanner andcomputer 7 to track with the target as evidenced by indicators 6' and6". The scanner 1, in effect, operates to produce a radio line of sightin the same way as the sighting telescope in a conventionalanti-aircraft or inter-aircraft system operates to produce an opticalline of sight, to enable the cornputer 7 to track with the presentposition of the target, whereby the proper gun aiming angles aredetermined.

A second type of tracking operation is illustrated in Fig. 3 and istermed semi-automatic tracking. In this case the scanner 1, againperforming circular conical scanning as described with respect to Fig.2, is caused to automatically align its orientation with that of thetarget. This is done by using the reflected pulses received from thetarget to actuate suitable servo motors for orienting the scanner, whichis thereby automatically oriented toward and tracks with the target. Thecomputer 7 is again manually controlled from controls 8, in thisinstance to follow and track with the orientation of scanner 1. Thus,tracking indicator 6' in this type of system serves to indicate thedisplacement between the orientations of scanner 1 and computer 7, andcomputer 7 is actuated to maintain this computer error at zero. Whenthis condition obtains, and with the proper computer range adjustment,similar to that described in Fig. 2, the output of computer 7,controlling guns 9, again represents the proper gun aiming angles andetective re may be obtained from the guns.

Fig. 4 shows the third or full automatic tracking system in which nomanual actuation is necessary. Here, scanner 1 is automatically orientedtoward the target, underV the control of the output of receiver 4, as inFig. 3, and, in addition, the orientation of computer 7 is caused toautomatically follow the position of scanner 1 by a suitable servomechanism. In this manner, the proper target azimuth and elevation dataare set into the computer 7. The rangeV adjustmentof computer 7 is alsoautomatically performed by a range control 10 under the control ofreceiver 4. This system, however, does not obtain the target rates, thatis, elevation rate and azimuth4 rate, in the same manner as in Figs. 2and 3.

In the system of Fig. 4, it is necessary to determine elevation rate andazimuth rate by actually measuring the angular rate of motion of theazimuth and elevation input controls of scanner 1. This may be done inany well known way, such asis shown and described in U. S. Patent No.2,206,875, for Fire Control Device, issued July 9, 1940, in the name ofE. W. Chafee et al. In this manner, all the required data may be setinto computer 7 and therefore the guns 9 are automatically oriented atthe :meegaat:

proper gun.v aiming angles and automatically follow :the target.

RI-ndicatorfnin this instance merely serves yas .a monitor indicator toshow'how-wellithe Vscanner 1 is following the targetor, alternatively,how well ithe computer 7 is following and tracking with scanner `1.Indicator 6" serves similarly as a range monitor indicator.

The system ,is therefore capable of four alternative modes of operation,namely, searching, manual tracking, semi-automatic tracking, and fullautomatic tracking.

Fig. shows a' schematic representation of one suitable typevot`scanner 1. Thus, the scanner 1 may comprise a directive antennasystem 3,shown as comprising a parabolic :wave guide reector, and energizedthrough suitable electromagnetic'wave guide connections 11 fromtransmitter v2. Av suitable construction for scanner 1 is shown anddescribed in copending application Serial No. 438,388, for :ScanningDevices, led April 10, 1942, in the names'of L. A.Maybarduk, W. W.Mieher, S. J. Zand and 1G. E. White, Lwhich issued on November 12, 1946,fas U. S. Patent No. 2,410,831. As therein disclosed, the antennaarrangement 3 in one form may be continuously nodded or oscillated at aslow rate about nod ,axis 12 which is itself rapidly and continuouslyrotated -or spun about spin axis 13 thereby producing a spiral conicalscanning pattern by the .continuous widening of the conical sweepingabout spin axis 13. To convert from the spiral searching scanning to thecircular tracking scanning, A'the nod motion about the nod axis 12 isinterrupted, withthe orientation of the directiveradiation orreceptivity .pattern axis 21 displaced slightly from the spinaxis 13.

In order to feed radiant energy from wave guide 11 to the radiator 3,suitable stationary joints 14 and lrotating joints 16 are provided asdescribed more in detail in the above-mentioned eopending applicationSerial No. 438,- 388, (now U. S.'Patent No. 2,410,831), and in copendingapplication Serial No. 447,524, for High Frequency Apparatus,.led June18, 1942 yin the names of W. W. Mieher and J. Mallet, which issued onSeptember 10, 1946 as U. S. zP-atent No. 2,407,3 18.

To'zprovide -the necessary `control of tracking indicator .6' .fromscanner 1, in the manner to be described, suitable .self-synchronousposition transmitters are provided forproducing signals indicative oftheinstantaneous positionfof'lthe radiator 3 in nod and in spin, that is,indicative of theforientation ofaxis 21. The nod transmitter isindicatedfschernaticall-y at 17, the spin'transmitter at 18. Thesetransmitters may beof the well known Selsyn, Autosyn or .'Te'legontypes.

Referring to Fig. 6, Ithere `isfshown the radiation or receptivitypattern 19, of the'antenna array 3.of Fig.v 5. It will be noted thatthis radiation pattern r19 preferably is axially symmetrical about raxis2/1, and is substantially contained within a narrow solid cone 22,thereby forming a sharply=directive beam of transmitted energy or asharply directive .reception pattern. Pattern 19 Vhas beenexaggerated-for purposes ofwillustration, and preferably-is very narrow,such as -about 4 between the half-power points. During .searchingoperations the axis 21 of this beam .19, by virtue ofthe combined'effectof the nodding andspinning action-of scanner 1,.is .caused to sweepout aspiralcone inspace, the-solid-angleof this sweep being suitably.chosenandrangingY up to a complete hemisphere as desired. Preferably,.theangular pitch of this spiral is chosen to bewof the order of theeifective'angular width of thebeam-19 whereby, during one completespiral scan every ,portion of `thewconical solid angle will have hadradiantenergy projected to it, and radiant enelgymay bereceivedfromevery-suchgportion. The'rates'of nod and spiny ofthe scannerof Fig. 5.are suitably chosen to Vprovide a sufficiently shortV timeinterval fora complete scan,.suit able for the purposesat hand.

Duringft-rackingoperations-the nod motion'of scanner 1 ssstopped-fata-positionrsorthat-,the axis 21 Vof'irnaximum radiation orrreceptivity'istdisplaced slightly from the spin axis 13.*about whichthe radiation pattern 1-9 is rotated. 1n thisway, as shown1in Figs. 7yand 7A, energy of `constant `intensity is radiated Vor received along anaxis 23 coincident with ,spin a'xis'13. However, along someother axis,vsuch as 24, for'example, maximum lradiation and maximum receptivity islencountered only once .during each :spin cyc1e,resulting in a spinvfrequency modulation of -waves received by -reection Yfrom an objectoriented along axis 24.

The use of the same vantenna arrangement for `transmitting and receivingincreases the sharpness of the resulting determinations since theover-'all response pattern is the product ofthe radiation and-receptivity patterns. If desired, however,'anon-directional transmitter.or receiver could be used with the described scanner actingrespect-ivelyas a receiver or transmitter.

lConversion from searching to tracking scanning is effected, asdescribed inapplication Serial No. 438,388 (now U. S. Patent No.2,410,831), merely by energization of a suitable ycontrol solenoid.Other types of scanners are also described therein, requiring differentapparatusy-for converting Afromsearching to tracking, but all adapted tobe used for searching or tracking in the same manner as the scanner ofFig. 5.

Itmay also be desirable to adjust the Aaxis of this spiral scanningduring the searching operation. @For this purpose, scanner 1 vmayVbeprovicled with an elevation axis 26 andV anv azimuth axis. 27 aboutwhich it may be suitably adjusted,in vthe manner described inapplication Serial No. 438,388 V(now U. S. Patent No. 2,410,831), thecontrol action being as vdescribed below. Also, suitable elevation andazimuth position transmitters 28 and 2.9 may be used, as will also .bedescribedbelow.

Fig. y8 shows one form of -radio'and indicator system forgiving suitablevindications during searching. Thus, assuming that the scanner of Fig.f5 isl performing the spiral scanningdescribed above, -antenna array 3is fed with radiant .energy :as over wave guide 11, from a `transmitter.and vmodulator unit 31. This transmitter 31 is adapted to. producehigh, -frequencyradiant 'energy in any well known-manner, and to.modulate this high frequency energy by means .of periodically.recurringrshort duration pulses such as -may be derived from a'conventional control oscillator...and.,p.ulse generator 3.2. rThere isthus radiated from the radiatingarrangement 3 a sequence of short pulsesof high .frequency .radiant energy. The frequency of control oscillator'32 and `thereby the repetition frequency of the radiated pulses ischosen to have a suitably high value such -that a substantial number ofpulses is sent out during each spin rotation of the scanner 1 of Fig. 5..Suitable values for various constants of the circuits duringthis formof operatiorrhave been found to Abe the following: spin rotation, .1200revolutions per minute; nod-oscillation, 30 complete-oscillations perminute; pulserepetition frequency, 2000 per second. With these values itwill be seen that one complete cycle of spiral scanning will beaccomplished each two seconds, one Vsecond being taken up in a spiralscan from zero nod to full nod, the other second of the cycle comprisingthe time .for spiral scanning from `full nod back to zero nod. Duringeach half of the .complete cycle 20 complete spin rotations. areperformed. Thus, for a full hemisphere of scan, thefangularfiadvance'for each spin cycle will be approximately-41/2degrees, which is of the order ofmagnitude -of .the 'width of theradiation pattern 19 shown vin Fig. 6.j Thefpulserepetition rate of.2000 pulses per second :gives pulses, per spin rotation,which therebyproduces one pulse for each 3.6 degrees of motion of the radiationpattern 19 during scanning. Since the radiation patternfi19 .isvapproximately 4 vto 5 degrees wide, it will y'be seen Athat 'at leastlone pulse` of radiant energy is transmittedito-each point of thehemisphere.

Should .afrdistantfobject be'iinthe field of theV systemduringmadiaion,atleasbonezpulsezwill be incident there- 9V on, andrellected therefrom. This reflected pulse or pulses will be picked up inthe antenna arrangement 3 and c011-l ducted through wave guide 11 to thereceiver unit 4 through a T-R box 33. T-R box 33 is adapted to pass therelatively low intensity received pulses but to block out the relativelyhigh intensity transmitted pulses derived from transmitter 31. Asuitable form for such a T-R box 33 is shown in copending applicationSerial No.

406,494 for Radio Apparatus for the Detection and Location of Objects,liled August 12, 1941, in the names of I. Lyman et al. and comprises, asis therein shown, an ionizable medium containing a spark gap within aresonant cavity which is resonant to the high frequency of transmission.The spark gap is so adjusted that the loW intensity received waves areinsucient to create a discharge across the gap, Whereas the highintensity transmitted pulses are sufficient to create such a discharge,which thereby ionizes the ionizable medium and effectively shortcircuits the wave guide 11 to these transmitted waves. In this mannerthe receiver unit 4 is effectively isolated from the high intensitytransmitted pulses while being free to receive the pulses reliected froma distant object. Receiver unit 4 includes conventional preamplifying,detecting and wide-band amplifying units, all well known in the art, andis adapted to produce, in its output, signal currents or voltagescorresponding to the wave shape of the envelope of the vreceivedreflected wave.

The received pulses are applied to the control grid 37 of the cathoderay tube indicator 6 shown in Fig. 8. Grid 37 is provided with asuitable bias, as by way of lead 38, such that, with no output fromreceiver 4, the cathode ray beam, produced by the usual means, isprevented from reaching the screen of the cathode ray tube indicator 6.However, this bias is also so adjusted that the received pulses 36derived from the receiver unit 4 are permitted to momentarily render theelectron beam trace visible on the screen of indicator 6. Thus, it willbe clear that each `time a reected pulse is received a momentary brightspot occurs on the cathode ray screen.

In order to give an indication of the orientation of the reflectedobject with respect to the location `of the system of the invention itis desirable to produce a spiral scanning of `electron beam insynchronism with and corresponding instantaneously to the spiralscanning of the radiation and reception pattern 19. Suitable devices forobtaining deflecting voltages which will produce such a spiral scanningare shown in Figs. 9 through l2. Assuming, for the moment, that suchspiral sweep voltages,

designated as P1 and P2, have been obtained, these volty ages P1 and P2,to be hereafter described more in detail, are impressed upon respectivepairs of deecting plates of the cathode ray indicator 6 and produce aspiral scanning of the electron beam such that at each instant theorientation of the latent trace of the beam on the screen'of the cathoderay indicator 6 with respect to the screen center or pole 39 of Fig. 8A,corresponds to the instantaneous orientation of the beam axis 21 ofantenna array 3 of scanner 1. Under these conditions the momentarybrightening or intensifying of the electron beam under the control ofreceiver 4 will produce a momentary bright spot such as 41 shown in Fig.8A. If a plurality4 of objects having different orientations are withinthe effective -iield of the `searching system further bright spots suchas 42 and 43 will also be produced, each having an orientation withrespect to pole 39 respectively corresponding to the orientation of thecorresponding reliecting object with respect to the spin axis 13 of thescanner 1.

As described above, the transmitted pulses and hence the reflectedpulses are of quite short duration, such as the order of l microsecond.In order that the bright spots 41, 42 and 43 may be more clearly shownit is desira-v ble to let the beam impinge upon the screen for al longerinterval. between receiver 4 and intensity control grid 37. This Forthis purpose a signal storer 44 isinserted.

signal storer' 44 may simply comprise a condenser-resistor networkadapted to be instantaneously charged by a pulse derived from receiver 4and which will maintain its charge beyond the duration of the pulse.However, the time constant of the signal storer 44 is preferably sochosen that this accumulated charge will be fully dissipated within atime not much longer than one recurrence period of the transmittedpulses in order that erroneous indications shall not be obtained. Inthis way the traces 41, 42, 43 are made brighter. In addition, thescreen of indicator 6 is preferably made of high retentivity, so as tomaintain its indication for a substantial interval after excitation isremoved.

Fig. 9 shows one form of circuit for producing the spiral sweep voltagesused with indicator 6 of Fig. 8. In this figure, nod transmitter 17 isindicated as being of a two-phase type having a single-phase energizingwinding 46 and a two-phase secondary Winding 47, in this instanceconnected in series to provide a single output. Winding 46 is energizedfrom a suitable source 48 of alternating current. The output voltageappearing across the polyphase winding 47 namely voltage V1 having waveshape as shown in Fig. 10A, will therefore be an alternating voltagehaving the frequency of source 48 and an amplitude varying incorrespondence with the amount of nod, referred to the orientation ofthe scanner spin axis as zero nod. This wave is shown in Fig. 10A, beingillustrated as having a linear change of amplitude with nod. It is to benoted that ordinarily this change of amplitude will besinusoidal incharacter. However, by the'use of proper motion converting Vdeviceswhereby full nod motion corresponds to a small'angular displacement ofwinding 46 with respect to winding 47, it may be made linear asillustrated. Preferably full nod is made to correspond to less than 45rotation of transmitter 17, resulting thereby in substantially linearoutput as shown in Fig. 10A.

During searching operations, switch 49 will be connected to terminal Sand hence the output voltage V1 of nod transmitter 17 is fed to thesingle-phase winding 51 of the spin transmitter 18. The output from eachof the two-phase windings 52 and 53 of spin transmitter 18 will then bethe Wave of Fig. 10A sinusoidally modulated in amplitude at thefrequency of spin; This is shown in Fig. 10B for the winding 52. Thewinding 53, being displaced in space with respect to Winding 52, willhave induced in it a voltage of similar wave shape but displaced 90 inphase at the spin frequency. In effect, spin transmitter 18 serves as `atwo-phase generator of spin frequency whose output amplitude iscontrolled by nod transmitter 17.

To each of these voltages Voutput from windings 52 and 53 there is addeda voltage of the frequency of source 48, as by way of transformer 54,producing the wave shown in Fig. 10C. Itis to be noted that the wave ofFig. 10B represents in effect a suppressed-carrier modulated wave. vThere-insertion of the carrier as by transformer 54 produces the usualmodulated carrier wave shown in Fig. 10C. The resulting two waves arethen rectified or detected in respective rectiiiers 56 and 57 andfiltered in filters 58 and 59 to produce the output voltages appearingon output leads 61 and 62 having the wave shape shown in Fig. 10D,namely, phase-displaced voltages of spin frequency modulated by the Vnodwave envelope.

These two voltages appearing on lines 61 and 62 will be phase displacedby 90 of the spin frequency. They willbe termed the spiral sweepvoltages P1 and P2, respectively. As is well known, if two voltages ofequal amplitude and frequency, phase displaced by 90, are impressed onthe respective pairs of deecting plates of a cathode ray tube, theresulting trace of the electron beam will be circular. By simultaneouslyvarying the amplitudes of the two voltages the diameter of the circlewill be varied.

In the present instance, by using the two waves P1 11 and P2 asthedeecting voltages, the beam will'be caused to produce a circularipatternof constantly -changing diameter and will therebyA produce Ia spiralpattern- `simi-lar to the pattern swept out` in space by the scanner 1.It will, therefore, be clear that these voltages P1 and P2 areparticularly suited for use in indicator 6.

During any of the three types of tracking, not transmitter 17 isdisconnected from spin transmitter 18 by switch 49, which then connectswinding 51 of spin transmitter 1S to a'ixed source of alternatingvoltage, such as source 48, as by way of lead50. In this case, outputsweep voltages P1 and Pzfwill have constant amplitude, producing acircular trace on indicator 6, and accordingly will'be ,termed fcircularsweep voltages.

Fig. 11 shows an lalternative circuit for inserti-ng the carrier anddemodulating thewavesproduced by spin transmitter 18Y to producethesweep voltages P1and P2. Thus, here the respective outputs of windings52 and 53 are impressed uponthe gridsof respective detector ordemodulatortubes 63 and 64 whose plate circuits are energizedsimultaneonslyfrom .alternating voltage source 48. By properly phasingthe anode voltage .with respect to thegrid voltages, and by filteringout all Ycarrier frequency components, .as in lters 58 and 59,'the sametype of spiral sweep voltages P1 and Pz-will be obtained as in Fig. 9.

During spiral scanning and searching it is desirable to be able toadjust the orientation of the spin axis 13 of the scanner and, hence, tochange' the space orientation corresponding to the pole 39 .of theindication shown in Figs. 8A or 13A. For this. purpose, referring now toFigs. 12 and 5, scanner 1 is provided with azimuth and elevation servodevices, such as 82 and 83, respectively, adapted to actuate the scannerl about azimuth axis. 27 and elevation axis 26, as shown in Fig. 5.These servo devices may be of any well known type adapted to positiontheir outputs in accordance with suitable input voltages. Their detailsform no part of the presenty invention.

Also coupledv to azimuthaxis 27 is azimuth self-synchronous transmitter29 of any conventional type, and correspondingly coupled to elevationaxis 26 is elevation transmitter 28. As is well known, thesetransmitters 29 and 28 are provided with alternating voltage of asuitable frequency, such as from source 48, and their respective outputs84 and -86 correspond to the instantaneous orientation of spin axis 13in azimuth and elevation.

Computer 7 isalso provided with similar self-synchronous devices -87 and88 actuated respectively by the elevation and azimuth input settings ofcomputer 7. These devices are connected to the outputs 84 and 86 ofscanner transmitters 29 and 28 and serve as synchronous transformers orsignal generators, as is well known, to produce in thei'r outputs 89 and91 alternating signal voltages corresponding in phase and magnitude tothe sense and magnitude of relative displacement between the scannerorientation and the computer setting along the respective azimuth andelevation components. These outputs 89 and 91 control respective phasesensitive amplifiers 92 and 93 which thereupon control the respectiveservos 82 and 83 of the scanner 1 to reposition scanner 1 intocorrespondence with the setting of computer 7.

In this manner, by suitable control of computer 7, as by its manualorientation control 8, scanner 1 is caused to follow the orientationsetting of computer 7 and its orientation may be thereby adjusted asdesired.

The above action serves to set the orientation of the distant object ortarget in terms of its azimuth and elevation coordinates into computer7, when the scanner and target orientations coincide. For properoperation of computer 7, however, to permit the determination of thecorrect gun aiming angles, it is also necessary to :set therein ydatacorresponding tothe rangeof the. target. For

this `.purpose range pedal 10 is provided, which is actuated inthexmanner .to be described.

As is well known, in a system of the present type using reflectedpulses, the time interval or delay between the transmitted pulse and itscorresponding reflected pulse is directly proportional to the distanceor range of the reflecting object or target. Fig. 13 shows one type ofindicatingdevice useful for setting this range data into computer 7.Thus, control oscillator 32a serves to energize and synchronize asuitable wave squaring device 32b ofrany desired type producing a squarewave output having the same frequency as that of control oscillator 32a.This output actuates a pulse generator 32C of conventional designsuitable for deriving pulses for controlling the transmitter-modulator31 which produces the transmitted pulses. The received reflected pulsesare passed by T-R box 33 in the manner already described, and actuatethe receiver 4 to produce in its output, such asf94, a signal voltagehaving a wave shape similar to the envelope of the received wave, whichmay comprise a series of pulses of different amplitudes occurringbetween successive radiated pulses.

Control oscillator 32a also feeds a variable phase shifter 96 of anysuitable type whose output wave shape is then squared in a suitable wavesquarer 97, which may be similar'to wave squarer 32b, to derive a squarewave output havingxa frequency identical with that of control oscillator32a, but adjustable in phase position with respect vthereto by means ofphase shifter 96. It will thus be clear that the phase of the squarewave output of wave squarer 97 is adjustable also with respect to thetransmitted pulses and to the received pulses.

Wave squarer 32b also controls a conventional type of sweep circuit 98to derive in its output a suitable sawtooth sweep voltage which isimpressed upon the horizontal ldeile-,cting plates 99 of cathode rayindicator 6 to provide the time base trace for the indications to bedescribed. The sweep voltage preferably is constant for a half-cycle andvarying during the other half cycle whereby only a half-period isindicated on the screen of indicator 6".

The outputs of receiver unit 4 and of wave squarer 97 are combinedsuitably, as by superposition or addition, andarethen applied to thevertical deflecting plates 101 of indicator 6". Grid 37 of tube 6 issuitably biased to produce a beam trace. There will thereby be producedon the cathode ray screen of indicator 6 an indication similar to thatshown in Fig. 13A, in which representations of the received pulses, suchas 36, are superposed on a step 102.derived from and representative ofthe square wave output of wave squarer 97. The position of this step 102relative to the received pulses 36 is under the Vcontrol `of the settingof phase shifter 96, since, as described above, the phase of the outputof wave squarer 97 -with respect to the received pulses 36 may beadjusted by phase shifter 96.

In operation, the operator will choose a suitable one of these pulses 36corresponding to the target he wishes to attack, and will then match upthe range index step 102 with vthe desired pulse. In order to effectthis result he must suitably adjust the phase shifter 96. Preferably,this adjustment is made by means of a foot pedal such as 10, to which isalso coupled mechanically the range input of computer 7.. The amount ofphase shift produced in phase shifter 96 to match the range index 102with the desired received pulse 36 will be proportional to the actualrange of the target. Hence, it is merely necessary to directly couplepedal 10 or other means operable with phase-adjusting means `96 into thecomputer 7 to actuate the computer range control in the desired manner.

Fig. 14 shows a modification of Fig. 13. Here the transmitting .andreceiving circuits are the same as in Fig. 13. However, controloscillator 32a and adjustable phase :shifter 96 serve to. actuate asuitable pulse generator liadapted to producea'pulse of fixedmagnitudeand `13 Y of predetermined duration. The duration of this pulseis preferably chosen to be substantially of the order of the duration ofthe reflected pulses, or slightly longer.

With switch 104 thrown to the left position, this pulse output of pulsegenerator 103 is combined with the output 94 of receiver unit 4 in amanner similar to that of Fig. 13, resulting in the indication shown inFig. 14A, in which the output of pulse generator 103 provides a type ofpedestal representation 106 which, when matched to the desired receivedpulse representation, such as 36a, assures the proper setting of therange input to the computer 7. If desired, pedestal 106 may be madenegative resulting in a somewhat modied indication.

When switch 104 is thrown to the right position, a different type ofindication is provided, shown in Fig. 14B. In this instance, thevertical deflecting plates of indicator 6" are controlled solely by thereceived wave envelope 36 obtained from output 94 of receiver 4. Thepulse output of generator 103 is now applied to the intensity controlgrid 37 of indicator 6. Therefore, during the occurrence of thesepulses, the intensity of the cathode ray beam is made greater than itsintensity during the remaining portions of the sweep.

Thus, as shown in Fig. 14B, to perform range tracking the operator orgunner will adjust phase shifter 96, and hence the computer rangesetting, by means of range pedal 10 until the particular reflected pulse36a corresponding to the desired target is indicated on the indicatorscreen with increased intensity or brightness, as shown in Fig. 14B.

The type of range control illustrated in Figs. l2, 13, and 14, isparticularly adapted for use during both the manual tracking andsemi-automatic tracking operations, illustrated in Figs. 2 and 3.

Although the apparatus of the present invention has been described, forexemplary purposes, as embodied in a radar ranging system involving thetransmission from and reception of radio waves at the same location, itis to be understood that the apparatus may as well be employed insystems wherein the two waves to be phase compared are radiated fromlocations remote from the receiver. Thus a local index wave is generatedin timed relation to one of the received waves and compared as toposition with the other wave on a cathode ray tube.

Since many changes could be made in the above construction and manyapparently widely different embodiments of this invention could be madewithout departing from the scope thereof, it is intended that all mattercontained in the above description or shown in the accompanying drawingsshall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

l. Apparatus for positioning a member in accordance with the range of adistant object comprising antenna means for radiating a wave ofelectromagnetic energy and for receiving energy reiiected from saidobject, a receiver for supplying an output wave corresponding to saidreceived energy, a cathode ray tube including vertical and horizontalbeam-deflected means therefor and means for providing a base trace onthe face thereof in timed relation with said radiated wave, means forproducing a local index wave synchronously with said radiated wave, saidindex wave being a square wave of a length appreciably greater than thelength of said transmitted wave such that said index wave and saidreceiver output wave when applied to said deecting means of said cathoderay tube form traces representative thereof, said index Waverepresentation having a substantially at top portion displaced from andsubstantially parallel to said base trace and said output waverepresentation being in the form of a pip extending substantiallyperpendicularly from said base trace, said Waves being relativelyadjustable by an operator over the entire base trace to place thereceived wave representation at a desired location on and along the topportion of said index wave representation, means for applying said indexwave and said receiver output wave-to said beam deliecting means of saidcathode ray tube, adjustable phase shifting means for shifting the phaserelation between said received wave and said local index wave, and amember for adjusting said phase shifting means whereby said receiveroutput wave representation may be placed at a prescribed location'onsaid flat top portion of said index wave representation therebyproducing an accurate phase comparison of said waves and an accuratepositioning of said member in accordance with the range of said object.

2. Apparatus as set forth in claim l, wherein said index square wave isVof a length greater than the length of said receiver output wave but isshorter than said base trace such as to thereby form a fiat-toppedpedestal representation, and said prescribed position is on the flat topof said pedestal.

3. Apparatus as set forth in claim 1, wherein said index squarewave isof a length much greater than said receiver output wave and greater thanthe length of said' base trace such that the representation thereof isin the form of a step in said base trace and said prescribed position ison the edge of said step.

4. Apparatus for measuring the range of a distant object comprisingmeans for transmitting a periodic pulse Wave of electromagnetic energy,means responsive to pulses reflected by said object for supplying outputpulses corresponding thereto, a cathode ray tube having vertical andhorizontal beam-deflecting means therefor and means connected with saidhorizontal deflection means for producing a substantially linear basetrace across the diameter of said tube face in timed relation with saidtransmitted pulse wave, means for producing a local index wave in timedrelation to the transmitted pulse wave, said index wave being a squarewave of a length greater than the length of said transmitted pulse wavesuch that said index wave and said receiver output pulse when applied tosaid vertical deiiecting means form traces representative thereof, saidindex wave representation having a iiat top portion displaced from andparallel to said base trace and said output wave representation being inthe form of a pip extending substantially perpendicularly from said basetrace, said waves being relatively adjustable by an operator over theentire base trace to place said received pulse representation at adesired location on and along said top portion of said index waverepresentation, means for applying said index wave and said output pulseto said vertical beam-deiiecting means of Said cathode ray tube, meansfor adjusting the phase relation between said local index wave and saidtransmitted wave whereby said local index wave representation and saidreceived pulse representation may be relatively shifted to place saidreceived pulse representation at said prescribed position on said indexwave, and means operable with said phaseadjusting means for providing ameasure of the range of said object when said local wave and saidreceived pulse are so positioned.

5. Apparatus as in claim 4 wherein said index wave comprises a pedestalvoltage wave having a at top, the length of said pedestal wave beinggreater than the length of said received pulse but less than said basetrace such that the entire wave is represented on the face of saidcathode ray tube and said prescribed position of said received pulserepresentation relative thereto is on the Hat top thereof.

6. Apparatus as set forth in claim 4, wherein said index square wave isof a length much greater than said receiver output wave and greater thanthe length of said base trace such that the representation thereof is inthe form of a step in said base trace and said prescribed position is onthe edge of said step.

7. Apparatus for determining the time difference between a first radiowave and a second radio wave related in time to said rst radio waveincluding a cathode ray tube having vertical and horizontalbeam-.deflecting means therefor and means connected with .saidhorizontal deecting means for producing a substantially llinear basetrace across said tube face in timed relation with said rst wave, meansfor producing a local index wave'in timed relation to 4said iirst wave,saidindex wave being a square wave of va lengthv `greater than thelength of vsaid second wave Such that said index wavefand said secondWave when applied to said'vertical deflection -means of said cathode rayytube form traces representative thereof, said index wave representationhaving-a at top portiondisplaced from and parallel to said base traceand said second wave representation being in the form of a pip extendingsubstantially perpendicularly from said base trace, said waves beingrelatively adjustable by an operator over the entire base trace to placesaid second wave representation at a desired position' on and along saidindex wave representation, means for applying said index wave and saidsecond wave to said vertical beam-deect ing means of said cathode raytube, means for adjusting the phase relation between said index wave andsaid second wave whereby said index wave and said second waverepresentations may be relatively shifted to place said second waverepresentation at a prescribed'position on said at top portion ofsaidindex wave representation, and means operable with saidphase-adjusting means for providing a measure of the timedifferencebetween said rst Wave and said second wave when said index waverepresentation and said second wave representation are so positioned.

8. Apparatus vas claimed'in claim 7 wherein said localindexfwavecomprises a pedestal voltage wave having a flat top,the-length thereof being greater than'the length of said second wave butless than .the-length, of said base trace suchwthat the entire waverepresentation is visible on the face `offsaid 4cathode ray tube andsaid prescribed position of said second Wave representation is on the attop thereof.

9. Apparatus yas claimed vin claim 7 wherein said local wave is of alength much greater than the length of said second wave and the lengthof said base trace such that when applied to the vertical deflectionmeans of said cathode ray tube a representationof only one end thereofis visible to thereby produce .an indication of stepped configurationand said prescribedposition of said second wave representation is on theedge of the step produced by said local wave.

References Cited in the ile of this patent UNITED STATES PATENTS

